Many different video coding techniques have been developed for encoding and decoding of digital video sequences. The Moving Picture Experts Group (MPEG), for example, has developed several encoding standards including MPEG-1, MPEG-2 and MPEG-4. Other example coding techniques include those set forth in the standards developed by the International Telecommunication Union (ITU), such as the ITU-T H.263 standard, and the ITU-T H.264 standard and its counterpart, ISO/IEC MPEG-4, Part 10, i.e., Advanced Video Coding (AVC). These and other video coding techniques support efficient transmission of video sequences by encoding data in a compressed manner.
Video compression may involve spatial and/or temporal prediction to reduce redundancy inherent in a video sequence. In other words, video compression attempts to reduce the amount of data that needs to be transmitted between devices in order to communicate a given video sequence. Intra-coding uses spatial prediction to reduce spatial redundancy of video blocks within the same video frame. Inter-coding uses temporal prediction to reduce temporal redundancy between video blocks in successive video frames. For inter-coding, a video encoder performs motion estimation to generate motion vectors indicating displacement of video blocks relative to corresponding prediction video blocks in one or more reference frames. The video encoder performs motion compensation to generate a prediction video block from the reference frame, and forms a residual video block by subtracting the prediction video block from the original video block being coded.
Frame skipping may also be implemented by encoding devices and decoding devices to reduce the amount of data that needs to be transmitted between devices. In general, frame skipping refers to techniques in which the processing, encoding, decoding, transmission, or display of one or more frames is purposely avoided at the encoder or at the decoder. For example, instead of compressing and sending each frame in a 30 frames per second (fps) bit-stream, every other frame may be skipped during the encoding process resulting in a temporal resolution of 15 fps. Although frame skipping may effectively improve transmission efficiency, the reduction of the temporal resolution of the frame sequence may result in the introduction of temporal domain artifacts such as motion jerkiness which may significantly degrade the visual quality of the decoded video.